if p < r; q = Partition(A,p,r) Quicksort(A,p,q - 1) Quicksort(A,q + 1,r)

i = p-1 for j = p to r-1 if A[j] ≤ A[r] i = i + 1 exchange A[i] with A[j] exchange A[i+1] with A[r] return i+1